1. Field of the Invention
The invention relates to a high pressure gas supply system that supplies high pressure gas to a gas consuming apparatus, and a fuel cell system provided with this high pressure gas supply system.
2. Description of the Related Art
In recent years, vehicles driven by combustion energy of fuel gas and electric energy generated by an electrochemical reaction of fuel gas have been developed. Fuel gas such as natural gas and hydrogen is stored in high pressure gas tanks provided in these vehicles. Also, stationary fuel cell systems provided with fuel cells that induce an electrochemical reaction of fuel gas as a power source for generating electricity are also becoming more prevalent.
Because stationary fuel cell systems or fuel cell systems for vehicles may be started in a low temperature environment, Japanese Patent Application Publication No. 2005-158426 (JP-A-2005-158426), for example, proposes technology that attempts to prevent moisture from freezing.
While JP-A-2005-158426 attempts to prevent moisture in a hydrogen pump in a line from freezing by driving the pump when the system stops in order to remove water in the pump, presently little is done for a pressure decrease valve (i.e., a pressure regulating valve) disposed in a hydrogen gas line. For example, a pressure decrease valve uses a rubber diaphragm, and the rubber hardness of this rubber diaphragm naturally increases in a low temperature environment, so there is a possibility that the responsiveness of the diaphragm will decrease. Reduced responsiveness of the diaphragm affects the stability of the regulated pressure, which leads to a decrease in the pressure regulating function. With the technology proposed in JP-A-2005-158426, it is necessary to continuously operate a hydrogen pump that provides gas ventilation with adiabatic compression in order to avoid this decrease in function, so an improvement is now needed. Incidentally, this problem is not limited to a pressure decrease valve. That is, a similar problem also occurs when an apparatus that may suffer a decrease in function due to a decrease in temperature is disposed in a hydrogen gas line.